Selectorized dumbbells are well known in the exercise equipment art for allowing a user to quickly and easily adjust the exercise mass of the dumbbell rather than having to rely on a set of dumbbells that are individually non-adjustable but each provide a different exercise mass. For example, rather than having to purchase and store a set of ten different dumbbells to provide a user with the ability to pick an exercise mass that starts at five pounds and ends at fifty pounds in five pound increments, a user can purchase and store a single selectorized dumbbell to accomplish the same functionality. The exercise mass of the selectorized dumbbell is adjusted by a selector that cooperates with the handle of the dumbbell with the selector being adjusted relative to the handle by the user to selectively couple different numbers of weights to the handle. If the user wishes a lighter exercise mass, the user adjusts the selector in a manner that couples fewer weights to the handle. If the user wishes a heavier exercise mass, the user correspondingly adjusts the selector in a manner that couples a greater number of weights to the handle.
The PowerBlock® selectorized dumbbell, manufactured and sold by PowerBlock, Inc. of Owatonna, Minn., uses a series of nested exercise weights in which each weight comprises a left weight plate and a right weight plate which are spaced apart from one another but which are joined to one another to form a single weight by a front rail and a rear rail extending between and fixedly fastened to front and rear sides of the weight plates. Each weight in the series of weights have the weight plates spaced apart at progressively larger distances beginning with an innermost weight that is nearest to the handle and an outermost weight that is furthest from the handle. The front and rear rails in each weight are progressively longer to take into account the progressively increasing distances between the weight plates of the different weights. In addition, the rails are attached at progressively lower heights on the weights beginning with the innermost weight and ending with the outermost weight. Thus, the weights can be nested together in a compact assembly forming a set of nested left weight plates disposed adjacent the left end of the handle, a set of nested right weight plates disposed adjacent the right end of the handle, and with the handle capable of being dropped down into the gap that is formed between the sets of nested left and right weight plates. U.S. Pat. Nos. 7,335,142, 7,387,696 and 7,857,735 illustrate the above described structure of the PowerBlock® selectorized dumbbell.
The rails in each weight of the series of nested weights used in the PowerBlock® selectorized dumbbell have been attached to the front and rear sides of the weight plates in different ways in different models of the dumbbell. In some models, the rails are welded to the front and rear sides of the weight plates. In other models, the front and rear sides of the weight plates contain outwardly projecting lugs with the ends of the rails being bolted by threaded fasteners to such lugs. In this bolted attachment model, the fasteners require a high degree of torque and precision to drive them in properly such that the fastening of the rails to the lugs is done at the factory as part of the overall manufacturing process to ensure quality. As a result, the completed dumbbell is shipped in an assembled form with the different weights being disposed in their nested configuration and with the handle being dropped down into the gap between the spaced sets of nested left and right weight plates. This requires a carton, shipping package or crate large enough to envelop the assembled dumbbell such that the dumbbell is not easily transportable by an end user once the end user removes the dumbbell from its original shipping enclosure and disposes of such enclosure.
Thus, there is a need in the art to provide a knock down form of this type of selectorized dumbbell including a way of easily disassembling and reassembling the weight plates and the rails in each of the nested weights and in more easily carrying the components of the dumbbell from place to place if the end user desires to do so. This invention is directed to satisfying such need.